In American literature, who is "Simon LeGris"?

I am not familar with "Simon LeGris" but there is a Simon Legree in
the American novel Uncle Tom's Cabin. More info on the book and author
can be found at:
 http://www.harrietbeecherstowecenter.org/programs/uncle.shtml

Here is a quote from the book referencing Simon.
"Simon Legree, Tom's third and final master, has Tom whipped to death
for refusing to deny his faith or betray the hiding place of two
runaway slave women."
Hope this is helpfull to you.